Embodiments of the subject matter disclosed herein generally relate to subject matter disclosed herein systems and methods for air intake filter assemblies and more particularly to combustion turbine air intake filter assemblies.
Filter-in-filter designs are commonly employed for use in combustion turbine air intake filtration systems. These filter designs typically incorporate a relatively coarse pre-filter as an initial filtration stage, followed by an intermediate grade filter. The particular pre-filter or intermediate filter may also be chosen to optimize the system against local environmental conditions to which the combustion turbine is exposed, for example, salt air. These two filters are utilized to remove the majority of contaminants that would otherwise adversely impact the much more costly final stage high efficiency filter and reduce its useful life as well as shield the turbine's components from airborne contaminants. A common, and less expensive and complex commercial alternative is to combine the pre-filter and the intermediate grade filter into a single filter, and to use that with the high efficiency filter in a two-filter assembly.
Regardless which arrangement is used, changeout of the entire assembly is costly, especially when failure of the more readily fouled initial stage filter(s) leads to premature failure of the high efficiency filter and/or exposure of the turbine to adverse conditions, such as corrosion from salt breakthrough. Therefore, changeout of the entire assembly may be remedied by more frequent changeouts, also leading to increased direct costs and may require that the turbine be shut down to facilitate changeout and/or minimize adverse environmental impacts on the turbine, thus contributing to indirect costs through lost or less efficient energy production. Moreover, changes in local conditions over time may alter optimal filter selection for efficient turbine operation, again leading to turbine inefficiencies, increased exposure of the turbine to adverse local conditions, or an increased need for changeout and alternate filter purchase.
Another problem related to the difficulty of changing filters without shutting down the generator is the with proper hermetic seating of filters on the exhaust manifold so that they do not allow unfiltered air to pass through the manifold. If proper care is not taken to align the filters and sealing rings when changing the filters, or if faulty or imperfect sealing rings are used, the filters may not be properly seated, and air passageways may develop through which unfiltered air may be drawn through the manifold and into the turbines. As noted, airborne contaminants are a major cause of turbine failure, or may cause costly unscheduled turbine maintenance.
U.S. Pat. No. 4,304,580 to Gehl et al. discloses air cleaners having replaceable filter cartridges, and particularly to such cleaners having both principal and safety filter functions so that the engine or other device being supplied with cleaned air is not directly open to the ambient atmosphere even if a principal filter undergoes catastrophic failure.
U.S. Pat. No. 7,087,166, to Sudo et al. discloses a filter element comprising a combination of an upstream filter and a downstream filter, wherein the upstream filter is replaceable. As a result, the life of the downstream filter is elongated while attaining the required purified level, and in addition, a smaller number of filters are required in order to obtain the same amount of filtrate compared to conventional filters.
U.S. Pat. No. 4,812,235 to Seleman et al. discloses a filter element constructed of stainless steel that includes a pair of filter media concentrically disposed to receive parallel flow of the filtrant. The element is adapted for disassembly to remove the filter media, allowing for the various component parts of the filter element to be easily cleaned and the filter media replaced.
U.S. Pat. No. 5,462,653 to Hills discloses a continuous polymer filtration apparatus employing parallel filter units that are opened and closed to shift flow from one filter to another to provide the operator with access to off-line filter segments for cleaning or replacing while fluid flow continues through the open filter segments.
U.S. Pat. No. 6,830,686 to Engelhard et al. discloses sealing elements at opposed ends of a filter cartridge to permit use of a single or axially stacked filter cartridges within a housing without compromising the seals necessary to prevent mixing of filtered and unfiltered fluids flowing through the housing.
What is needed are filter assemblies that allow an operator to extend the useful lifetimes for high efficiency filter components in air intake filter assemblies without adversely impacting energy production. Assemblies are also needed whereby an operator can replace filter stages in operational filter assemblies based on needs dictated by local conditions. New filter assemblies are also needed to allow changeouts independently of one or more filter stages, especially changeouts that can be made relatively quickly using simple tools to effect the changeout as compared to existing filter technologies. New filter assemblies are also needed that allow such changeouts while the turbine remains in operation, thus minimizing inefficiencies associated with shutdown and start up of the turbine. The subject matter disclosed herein is directed to these and other important ends.